Small Angle X-ray Scattering

Christopher J. Tassone

Stanford Synchrotron Radiation Lightsource

Materials Science Department

7th Annual SSRL Scattering School

An Overview

Outline

Overview of SAXS:

• Beamline Nuts & Bolts

• Calculating q-range

• SAXS Fundamentals and Scattering Patterns

• Real World Science Examples

• Moving into the future

- In-operando

- Probing materials off equilibrium

- In-situ growth

Beamline Nuts and Bolts

Calculating q-range

λ = 2dsin(θ)

Q = 2π/d

Easiest way to do this is to find your q/pixel

D S θpix

Xs-d

Xpix

To do this you need: •Detector Pixel Size

•Sample to detector distance

•Energy of incident x-ray photons

•Beamstop Size

•Detector Size

1) Solve for θpix

θpix = tan-1(xpix/xs-d)

2) Convert θpix to qpix

qpix = 4πsin(θpix)/λ

3) Find first real pixel p1= (rbstop/xpix)

4) qmin= qpix * p1

5) qmax= qpix * pdet/2

SAXS Fundamentals

Fundamentally looking at form factor scattering only:

I(q) = F(q)2Z(q)2

I(Q) = ∫Γn(r)e-iqrdr

Scattering from 1-100 nm density

inhomogeneities

k

2q

incident

scattered

k’

Q

SAXS Fundamentals

Fundamentally looking at form factor scattering only:

I(q) = F(q)2Z(q)2

I(Q) = ∫Γn(r)e-iqrdr

Scattering from 1-100 nm density

inhomogeneities

k

2q

incident

scattered

k’

Q

Understanding SAXS Profiles

• Guinier regime:

gives Rg, which is a measure

for the size of the particles

• Porod exponent:

provides

information about

shape of the

particles

polydisperse in

shape and/or size

Understanding SAXS Profiles

monodisperse in

shape and size

Form factor:

• depends on geometrical

shape of particles

• gives size and electron

density distribution of

particles

Understanding SAXS Profiles

Structure factor:

• Sequence of peaks Symmetry of structure

• Position of peaks Size of structure

• Width of peaks Size of domains/grains

• Intensity of peaks Degree of crystallinity

• Azimuthal distribution of peaks Orientation of domains

periodic

structures

10

Science at Beamline 1-5

Block-co-polymers

Mesoporous Materials

Nanomaterial Synthesis

Nanoparticle Characterization

Batteries/Energy Storage

Catalysts

Energy Generation Materials

11

Science Highlight-BCP Ordering

Rao, et. Al. Adv. Mater. 2010, 22, 5063. www.elitenetzwerk.bayern.de

Can we use BCP for:

• Improved transport in oFETs?

•Membranes for ionic transport?

Organic Electronics •Flexible

•Low cost

•Facile processing

•Light weight

12

Science Highlight-BCP Organization

Understanding BCP Phase Diagram through SAXS

Ho, Victor; Boudouris, B.W.; McCulloch, B.L.; Shuttle, C.G.; Burkhardt, M; Chabinyc, M.L.; Segalman, R.A. “Poly (3-alkylthiophene) Diblock

Copolymers wuth Ordered Microstructures and Continuous Semiconducting Pathways” J. Amer. Chem Soc. 133, 2011, 9270.

13

Science Highlight-BCP Templated Nanoparticle Films

Electrochemical

Charge Storage

TiO2 H2O

OH-

H2O

O2

O2-

CO2

+ Organic

Precursors Catalysts

Photovoltaics

Adv. Mater. 2011, 23, 3144

14

Science Highligh-BCP Templated Nanoparticle Films

Me

erw

in’s

Salt

BC

P

inco

rpo

ration

Film

Co

nd

en

sa

tion

Th

erm

al

Annealin

g

Rauda, I.E.; Saldariaga-Lopez, L.C.; Helms, B.A.; Schelhas, L.T.; Membreno, D.;

Milliron, D.J.; Tolbert, S.H. “Nanoporous Semiconductors Synthesized Through

Polymer Templating of Ligand-Stripped CdSe Nanocrystals.” Adv. Mater. 25, 2013.

1315.

PEO Domain

Aromatic Domain

Inter-domain

spacing

Inter-molecular

spacing

Domain

size

How Does Membrane Morphology Relate to

Ionic Conductivity?

•Use SAXS to characterize nano and

mesoscale morphology as a function of

PEG loading

•Random co-polymer PEO-PI

•Conductivity peaks when PEG loading

is high enough to observe PEO-PEO

domain correlations (20 nm)

Science Highlight-Random co-polymer Membranes

Controlling BHJ Morphology

Thermal

Annealing Increases

crystallinity

Increases phase

segregation

Solvent Additives Increases crystallinity

Increases or decreases phase segregation

More isotropic crystal distribution

No Post Processing

Solvent

Annealing Increases

crystallinity

Increases phase

segregation

Processing Additives Tune Morphology Uniquely

Processing additives… •enhance crystallinity

•increase isotropic distribution

of crystallites

•can increase or decrease

degree of phase segregation

Pure CB DIO

Liang, Y. et. Al. doi:10.1002/adma.200903528

OT Pure oDCB

J. Rogers et al., doi: 10.1021/ja2104747

Y.Yao et. al. doi:10.1002/adfm.200701459

How Does Solution Behavior Effect Solid Film

Formation?

How Does Solution Behavior Effect Solid Film

Formation?

?

Probing Solid State Film and Casting Solution

Solution SAXS

Solid State SAXS

Interpreting SAXS Data

Two Regimes •Guinier domain size

•Porod •Diffuseness of interface

between domains

•Shape of aggregate

Probing Solid State Film

Solution SAXS

Solid State SAXS

Processing Additives Decrease Phase Segregation

-2.7

-3.5

Visualizing Morphologies

Representative 3D morphologies

B. Ingham et al., doi:

10.1107/S00218898110048557

no additive

w/ ClN

w/ DIO

w/ ODT

Probing Casting Solution

Solution SAXS

Solid State SAXS

C16-PDPP2FT Solution Phase Conformation

10-4 10-3 10-2 10-110-3

10-2

10-1

1

101

102

103

104

105

106

Inte

nsi

ty[a

.u.]

q [Å-1]

41 kDa

36 kDa

29 kDa

23 kDa

q-3

q-1

‡‡

†

a)

Low Mn High Mn

b)

10-4 10-3 10-2 10-110-3

10-2

10-1

1

101

102

103

104

105

106

Inte

nsi

ty[a

.u.]

q [Å-1]

41 kDa

36 kDa

29 kDa

23 kDa

q-3

q-1

‡‡

†

a)

Low Mn High Mn

b)

Chloronapthalene has little effect on PCBM Aggregation

Neat CB

Increasing Concentration

Neat CB 5% CN

10-4 10-3 10-2 10-110-3

10-2

10-1

1

101

102

103

104

105

106

Inte

nsi

ty[a

.u.]

q [Å-1]

41 kDa

36 kDa

29 kDa

23 kDa

q-3

q-1

‡‡

†

a)

Low Mn High Mn

b)

Putting Together Polymer and Fullerene Behavior

5% CN

Neat CB

K. Schmidt. Adv. Mater. doi:10.1002/adma.201303622

Mechanism Summary

1. Additive promotes ordering within solution phase aggregates

2. PCBM stays well dispersed in solution with or without additive

3. Films cast with additive show small more intermixed domains

Weakly ordered polymer aggregates act as dispersed seed

sites for crystallization during film formation

30

Enabling Science Through Beamline Upgrades

• Characterization of disordered soft

materials

• Fuel cell membranes

• Organic Photovoltaics

• Bioelectronics

• Anatomical materials

31

Increasing In-situ Capabilities

• Increased in-situ capabilities

• Solution phase reactor

• Electrochemical fluid cell

- Battery materials

- Catalyst materials

- Electrochemical Capacitors

• Stress-strain curves

Dogbone

Force Transducer

32

In-situ Printing at BL 1-5

Print Film

Collect SAXS/WAXS

Extract Metrics

Change Printing

Conditions

Beamline Information

Website:

http://www-ssrl.slac.stanford.edu/content/beam-lines/beam-lines-

by-number (1-5 page under construction)

Deadlines:

Beamtime Requests

November - February scheduling August 20

February - May scheduling November 15

May - August scheduling February 15

New Proposals

Beam time eligibility beginning in February September 3

Beam time eligibility beginning in May December 1

My Info: tassone@slac.stanford.edu